Special counsel Robert Mueller reportedly has asked President Donald Trump’s attorneys about whether and how the president could be interviewed by investigators from Mueller’s office. The president’s lawyers apparently are also exploring options short of a live interview, such as having the president answer written questions or submit a sworn affidavit. With discussions at such an early stage, these talks could play out in many ways. But there are a few things about which we can be fairly confident.

First, it’s unlikely Mueller will conclude his investigation without at least attempting to question the president. The special counsel’s probe is focused on possible Russian interference with the election and contacts with the Trump campaign. Whether or not investigators suspect the president himself of wrongdoing, as the candidate at the head of that campaign he is a critical witness.

Second, the president’s lawyers would almost certainly prefer the president not have to talk to Mueller’s people at all. Again, even if they believe the president has done nothing wrong, there generally is little upside for the defence in submitting to a grilling by federal prosecutors. And although he may behave differently in a more formal setting, if the president’s Twitter feed and public statements are any guide, his lawyers have good reason to be concerned about what he might say.

If the president's Twitter feed and public statements are any guide, his lawyers have good reason to be concerned about what he might say

Third, Mueller’s team will not be satisfied with an affidavit or written responses to questions. It would be extremely unusual for prosecutors to agree to either for someone so central to their investigation. Prosecutors always want to eyeball a witness. They want to see his demeanour and body language, to see and hear how he reacts when confronted with difficult questions or contradictory information.

Written answers or an affidavit from the president would be carefully crafted in consultation with his lawyers. Sterile legalisms on a page would not give prosecutors the true measure of the president’s knowledge and state of mind, nor would they allow the probing followup questions that are the mark of a skilled examiner.

All that being said, this is a negotiation — and both sides have some leverage. As a legal matter, the president does not have to agree to answer questions at all. No citizen is required to submit to an interview by federal investigators. And although political conventional wisdom would suggest that refusing to co-operate is not a viable option, this president has successfully defied political convention before.

Special Counsel Robert Mueller departs the Capitol after a closed-door meeting with members of the Senate Judiciary Committee about Russian meddling in the election, in a photo taken on June 21, 2017.J. Scott Applewhite/AP

Suppose the president’s lawyers told Mueller, “It’s written responses to questions or nothing — take it or leave it.” Mueller would then have two options: agree or subpoena the president to the grand jury. There is a familiar precedent for the latter: independent counsel Kenneth Starr subpoenaed president Bill Clinton, who testified for several hours before a grand jury via video and audio link about his affair with Monica Lewinsky. But it’s possible Trump would not agree to comply and his lawyers would mount a constitutional challenge to the subpoena of a sitting president. That could delay Mueller’s investigation for months.

On the other hand, the president’s lawyers must consider that during a voluntary interview they can at least be in the room and participate. If Mueller called their bluff and subpoenaed the president and he ended up before a grand jury, prosecutors could examine him under oath with no defence attorney present. From a defence perspective, a voluntary interview accompanied by defence counsel is always preferable to having the client enter the lion’s den of the federal grand jury room alone.

An additional consideration for the defence will be whether the president should invoke his Fifth Amendment right to remain silent in response to a subpoena or an interview request. Again, in normal times that would seem like political suicide, but in our current political environment, who knows?

This is where the ongoing efforts by the president and his allies to discredit Mueller’s investigation and the FBI may come into play. If the president succeeds at painting the investigation as biased or illegitimate, it could give him the necessary political cover to refuse to co-operate in the “witch hunt” or even to take the Fifth. The Republican-controlled Congress thus far has given little indication it would make the president pay a political price for such a move.

This legal dance may continue for some time. In a more typical case, in the end the parties would likely reach some compromise to get prosecutors the information they needed. But, of course, this case is anything but typical. A dispute over the president’s testimony is just one more potential constitutional flashpoint in the Mueller investigation.

Randall D. Eliason teaches white-collar criminal law at George Washington University Law School. He blogs at Sidebarsblog.com.